RAS_WEB (Page 2,847)

$NuSTAR$ Observations of Four Nearby X-ray Faint AGN: Low Luminosity or Heavy Obscuration?. (arXiv:2006.13583v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Annuar_A/0/1/0/all/0/1">A. Annuar</a> (UKM), <a href="http://arxiv.org/find/astro-ph/1/au:+Alexander_D/0/1/0/all/0/1">D. M. Alexander</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gandhi_P/0/1/0/all/0/1">P. Gandhi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lansbury_G/0/1/0/all/0/1">G. B. Lansbury</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Asmus_D/0/1/0/all/0/1">D. Asmus</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Balokovic_M/0/1/0/all/0/1">M. Balokovic</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ballantyne_D/0/1/0/all/0/1">D. R. Ballantyne</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bauer_F/0/1/0/all/0/1">F. E. Bauer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Boorman_P/0/1/0/all/0/1">P. G. Boorman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brandt_W/0/1/0/all/0/1">W. N. Brandt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brightman_M/0/1/0/all/0/1">M. Brightman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chen_C/0/1/0/all/0/1">C.-T. J. Chen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Moro_A/0/1/0/all/0/1">A. Del Moro</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Farrah_D/0/1/0/all/0/1">D. Farrah</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Harrison_F/0/1/0/all/0/1">F. A. Harrison</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Koss_M/0/1/0/all/0/1">M. J. Koss</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lanz_L/0/1/0/all/0/1">L. Lanz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Marchesi_S/0/1/0/all/0/1">S. Marchesi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Masini_A/0/1/0/all/0/1">A. Masini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nardini_E/0/1/0/all/0/1">E. Nardini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ricci_C/0/1/0/all/0/1">C. Ricci</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stern_D/0/1/0/all/0/1">D. Stern</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zappacosta_L/0/1/0/all/0/1">L. Zappacosta</a> We present $NuSTAR$ observations of four active galactic nuclei (AGN)Read More →

Evaluation of the $^{13}$N($alpha$,p)$^{16}$O thermonuclear reaction rate and its impact on the isotopic composition of supernova grains. (arXiv:2006.13589v1 [nucl-ex]) <a href="http://arxiv.org/find/nucl-ex/1/au:+Meyer_A/0/1/0/all/0/1">A. Meyer</a>, <a href="http://arxiv.org/find/nucl-ex/1/au:+Sereville_N/0/1/0/all/0/1">N. de S&#xe9;r&#xe9;ville</a>, <a href="http://arxiv.org/find/nucl-ex/1/au:+Laird_A/0/1/0/all/0/1">A. M. Laird</a>, <a href="http://arxiv.org/find/nucl-ex/1/au:+Hammache_F/0/1/0/all/0/1">F. Hammache</a>, <a href="http://arxiv.org/find/nucl-ex/1/au:+Longland_R/0/1/0/all/0/1">R. Longland</a>, <a href="http://arxiv.org/find/nucl-ex/1/au:+Lawson_T/0/1/0/all/0/1">T. Lawson</a>, <a href="http://arxiv.org/find/nucl-ex/1/au:+Pignatari_M/0/1/0/all/0/1">M. Pignatari</a>, <a href="http://arxiv.org/find/nucl-ex/1/au:+Audouin_L/0/1/0/all/0/1">L. Audouin</a>, <a href="http://arxiv.org/find/nucl-ex/1/au:+Beaumel_D/0/1/0/all/0/1">D. Beaumel</a>, <a href="http://arxiv.org/find/nucl-ex/1/au:+Fortier_S/0/1/0/all/0/1">S. Fortier</a>, <a href="http://arxiv.org/find/nucl-ex/1/au:+Kiener_J/0/1/0/all/0/1">J. Kiener</a>, <a href="http://arxiv.org/find/nucl-ex/1/au:+Lefebvre_Schuhl_A/0/1/0/all/0/1">A. Lefebvre-Schuhl</a>, <a href="http://arxiv.org/find/nucl-ex/1/au:+Pellegriti_M/0/1/0/all/0/1">M. G. Pellegriti</a>, <a href="http://arxiv.org/find/nucl-ex/1/au:+Stanoiu_M/0/1/0/all/0/1">M. Stanoiu</a>, <a href="http://arxiv.org/find/nucl-ex/1/au:+Tatischeff_V/0/1/0/all/0/1">V. Tatischeff</a> It has been suggested that hydrogen ingestion into the helium shell of massive stars could lead to high $^{13}$C and $^{15}$N excesses when the shock of a core-collapse supernova passes through its helium shell. This prediction questions theRead More →

Spectrum formation in X-ray pulsars at very low mass accretion rate: Monte-Carlo approach. (arXiv:2006.13596v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Mushtukov_A/0/1/0/all/0/1">Alexander A. Mushtukov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Suleimanov_V/0/1/0/all/0/1">Valery F. Suleimanov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tsygankov_S/0/1/0/all/0/1">Sergey S. Tsygankov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zwart_S/0/1/0/all/0/1">Simon Portegies Zwart</a> It has been recently discovered that the transition of X-ray pulsars to the low luminosity state ($Llesssim 10^{35},{rm erg,s^{-1}}$) is accompanied by a dramatic spectral changes. Namely, the typical power-law-like spectrum with high energy cutoff transforms into a two-component structure with a possible cyclotron absorption feature on top of it. It was proposed that these spectral characteristics can be explained qualitatively by the emission of cyclotron photons in the atmosphere of the neutron starRead More →

Fiber positioning in microlens-fiber coupled integral field unit. (arXiv:2006.13601v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Chattopadhyay_S/0/1/0/all/0/1">Sabyasachi Chattopadhyay</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bershady_M/0/1/0/all/0/1">Matthew A. Bershady</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wolf_M/0/1/0/all/0/1">Marsha J. Wolf</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Smith_M/0/1/0/all/0/1">Michael P. Smith</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hauser_A/0/1/0/all/0/1">Andrew Hauser</a> A generic fiber positioning strategy and a fabrication path are presented for microlens-fiber-coupled integral field units. It is assumed that microlens-produced micro-images are carried to the spectrograph input through step-index,multi-mode fiber, but our results apply to micro-pupil reimaging applications as well. Considered are the performance trades between the filling percentage of the fiber core with the micro-image versus throughput and observing efficiency.A merit function is defined as the product of the transmission efficiency and the etendue loss.Read More →

Magnetic and Velocity Field Topology in Active Regions of Descending Phase of the Solar Cycle 23. (arXiv:2006.13602v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Maurya_R/0/1/0/all/0/1">R. A. Maurya</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ambastha_A/0/1/0/all/0/1">A. Ambastha</a> We analyse the topology of photospheric magnetic fields and sub-photospheric flows of several active regions (ARs) that are observed during the peak to descending phase of the solar cycle 23. Our analysis shows clear evidence of hemispheric preferences in all the topological parameters such as the magnetic, current and kinetic helicities, and the ‘curl-divergence’. We found that 68%(67%) ARs in the northern (southern) hemisphere with negative (positive) magnetic helicities. Same hemispheric preference sign is found for the current helicities inRead More →

The dichotomy of atmospheric escape in AU Mic b. (arXiv:2006.13606v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Carolan_S/0/1/0/all/0/1">S. Carolan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vidotto_A/0/1/0/all/0/1">A. A. Vidotto</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Plavchan_P/0/1/0/all/0/1">P. Plavchan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+DAngelo_C/0/1/0/all/0/1">C. Villarreal D&#x27;Angelo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hazra_G/0/1/0/all/0/1">G. Hazra</a> Here, we study the dichotomy of the escaping atmosphere of the newly discovered close-in exoplanet AU Mic b. On one hand, the high EUV stellar flux is expected to cause a strong atmospheric escape in AU Mic b. On the other hand, the wind of this young star is believed to be very strong, which could reduce or even inhibit the planet’s atmospheric escape. AU Mic is thought to have a wind mass-loss rate that is upRead More →

Transmission spectroscopy and Rossiter-McLaughlin measurements of the young Neptune orbiting AU Mic. (arXiv:2006.13609v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Palle_E/0/1/0/all/0/1">E. Palle</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Oshagh_M/0/1/0/all/0/1">M Oshagh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Casasayas_Barris_N/0/1/0/all/0/1">N. Casasayas-Barris</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hirano_T/0/1/0/all/0/1">T. Hirano</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stangret_M/0/1/0/all/0/1">M. Stangret</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Luque_R/0/1/0/all/0/1">R. Luque</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Strachan_J/0/1/0/all/0/1">J. Strachan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gaidos_E/0/1/0/all/0/1">E. Gaidos</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Anglada_Escude_G/0/1/0/all/0/1">G. Anglada-Escude</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Plavchan_P/0/1/0/all/0/1">P. Plavchan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Addison_B/0/1/0/all/0/1">B. Addison</a> AU Mic~b is a Neptune size planet on a 8.47-day orbit around the nearest pre-main sequence ($sim$20 Myr) star to the Sun, the bright (V=8.81) M dwarf AU Mic. The planet was preliminary detected in Doppler radial velocity time series and recently confirmed to be transiting with data from the TESS mission. AU Mic~b is likely to beRead More →

The high molecular gas content, and the efficient conversion of neutral into molecular gas, in jellyfish galaxies. (arXiv:2006.13612v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Moretti_A/0/1/0/all/0/1">A. Moretti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Paladino_R/0/1/0/all/0/1">R. Paladino</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Poggianti_B/0/1/0/all/0/1">B. M. Poggianti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Serra_P/0/1/0/all/0/1">P. Serra</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ramatsoku_M/0/1/0/all/0/1">M. Ramatsoku</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Franchetto_A/0/1/0/all/0/1">A. Franchetto</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Deb_T/0/1/0/all/0/1">T. Deb</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gullieuszik_M/0/1/0/all/0/1">M. Gullieuszik</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tomicic_N/0/1/0/all/0/1">N. Tomicic</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mingozzi_M/0/1/0/all/0/1">M. Mingozzi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vulcani_B/0/1/0/all/0/1">B. Vulcani</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Radovich_M/0/1/0/all/0/1">M. Radovich</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bettoni_D/0/1/0/all/0/1">D. Bettoni</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fritz_J/0/1/0/all/0/1">J. Fritz</a> In the disks of four jellyfish galaxies from the GASP sample at redshift $sim 0.05$ we detect molecular gas masses systematically higher than in field galaxies. These galaxies are being stripped of their gas by ram pressure from the intra cluster medium andRead More →

Multi-wavelength, spatially resolved modelling of HD 48682’s debris disc. (arXiv:2006.13614v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Hengst_S/0/1/0/all/0/1">Shane Hengst</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Marshall_J/0/1/0/all/0/1">Jonathan P. Marshall</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Horner_J/0/1/0/all/0/1">Jonathan Horner</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Marsden_S/0/1/0/all/0/1">Stephen C. Marsden</a> Asteroids and comets (planetesimals) are created in gas- and dust-rich protoplanetary discs. The presence of these planetesimals around main-sequence stars is usually inferred from the detection of excess continuum emission at infrared wavelengths from dust grains produced by destructive processes within these discs. Modelling of the disc structure and dust grain properties for those discs is often hindered by the absence of any meaningful constraint on the location and spatial extent of the disc. Multi-wavelength, spatially resolved imaging is thusRead More →

Evolution Of Downflows In The Transition Region Above A Sunspot Over Short Time-Scales. (arXiv:2006.13617v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Nelson_C/0/1/0/all/0/1">C. J. Nelson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Prasad_S/0/1/0/all/0/1">S. Krishna Prasad</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mathioudakis_M/0/1/0/all/0/1">M. Mathioudakis</a> Downflows with high velocities occur in the transition region above many sunspots; however, how these signatures evolve over short time-scales in both spatial and spectral terms is still unknown. In this article, we investigate the evolution of downflows detected within the transition region on time-scales of the order minutes and search for clues as to their formation mechanisms in co-temporal imaging data. The high-resolution spectral and imaging data used to identify downflows here were sampled by IRIS on theRead More →

An investigation of poorly studied open cluster NGC 4337 using multi-color photometric and Gaia DR2 astrometric data. (arXiv:2006.13618v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Bisht_D/0/1/0/all/0/1">D. Bisht</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Elsanhoury_W/0/1/0/all/0/1">W. H. Elsanhoury</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhu_Q/0/1/0/all/0/1">Qingfeng Zhu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sariya_D/0/1/0/all/0/1">Devesh P. Sariya</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yadav_R/0/1/0/all/0/1">R. K. S. Yadav</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rangwal_G/0/1/0/all/0/1">Geeta Rangwal</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Durgapal_A/0/1/0/all/0/1">Alok Durgapal</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jiang_I/0/1/0/all/0/1">Ing-Guey Jiang</a> We present a comprehensive analysis (photometric and kinematical) of poorly studied open cluster NGC 4337 using 2MASS, WISE, APASS, and Gaia~DR2 database. By determining the membership probabilities of stars, we identified 624 most probable members with membership probability higher than $50%$ by using proper motion and parallax data taken from Gaia~DR2. The mean proper motion of the clusterRead More →

Electroweak baryogenesis by primordial black holes in Brans-Dicke modified gravity. (arXiv:2006.13621v1 [gr-qc]) <a href="http://arxiv.org/find/gr-qc/1/au:+Aliferis_G/0/1/0/all/0/1">Georgios Aliferis</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Zarikas_V/0/1/0/all/0/1">Vasilios Zarikas</a> A successful baryogenesis mechanism is proposed in the cosmological framework of Brans-Dicke modified gravity. Primordial black holes with small mass are produced at the end of the Brans-Dicke field domination era. The Hawking radiation reheats a spherical region around every black hole to a high temperature and the electroweak symmetry is restored there. A domain wall is formed separating the region with the symmetric vacuum from the asymmetric region where electroweak baryogenesis takes place. First order phase transition is not needed. In Brans-Dicke cosmologies black hole accretionRead More →

Testing Ghasemi-Nodehi-Bambi spacetime with continuum-fitting method. (arXiv:2006.13628v1 [gr-qc]) <a href="http://arxiv.org/find/gr-qc/1/au:+Ghasemi_Nodehi_M/0/1/0/all/0/1">M. Ghasemi-Nodehi</a> The continuum-fitting method is the analysis of the thermal spectrum of the geometrically thin and optically thick accretion disk around stellar-mass black holes. A parametrization aiming to test the Kerr nature of astrophysical black holes was proposed in Ghasemi-Nodehi and Bambi in EPJC 76: 290, 2016. The metric contains 11 parameters in addition to the mass and spin parameters. One can recover the Kerr case by setting all parameters to one. In this paper, I study the continuum-fitting method in Ghasemi-Nodehi-Bambi background. I show the impact of each of the parameters on the spectra.Read More →

Interstellar glycolamide: A comprehensive rotational study and an astronomical search in Sgr B2(N). (arXiv:2006.13634v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Sanz_Novo_M/0/1/0/all/0/1">M. Sanz-Novo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Belloche_A/0/1/0/all/0/1">A. Belloche</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Alonso_J/0/1/0/all/0/1">J. L. Alonso</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kolesnikova_L/0/1/0/all/0/1">L. Kolesnikova</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Garrod_R/0/1/0/all/0/1">R. T. Garrod</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mata_S/0/1/0/all/0/1">S. Mata</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Muller_H/0/1/0/all/0/1">H. S. P. M&#xfc;ller</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Menten_K/0/1/0/all/0/1">K. M. Menten</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gong_Y/0/1/0/all/0/1">Y. Gong</a> Glycolamide is a glycine isomer and also one of the simplest derivatives of acetamide (e.g., one hydrogen atom is replaced with a hydroxyl group), which is a known interstellar molecule. Using a battery of state of the art rotational spectroscopic techniques in the frequency and time domain, around 1500 transitions have been newly assigned. Based on the reliableRead More →

The SUrvey for Pulsars and Extragalactic Radio Bursts V: Recent Discoveries and Full Timing Solutions. (arXiv:2006.13637v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Spiewak_R/0/1/0/all/0/1">R. Spiewak</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Flynn_C/0/1/0/all/0/1">C. Flynn</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Johnston_S/0/1/0/all/0/1">S. Johnston</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Keane_E/0/1/0/all/0/1">E. F. Keane</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bailes_M/0/1/0/all/0/1">M. Bailes</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Barr_E/0/1/0/all/0/1">E. D. Barr</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bhandari_S/0/1/0/all/0/1">S. Bhandari</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Burgay_M/0/1/0/all/0/1">M. Burgay</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jankowski_F/0/1/0/all/0/1">F. Jankowski</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kramer_M/0/1/0/all/0/1">M. Kramer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Morello_V/0/1/0/all/0/1">V. Morello</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Possenti_A/0/1/0/all/0/1">A. Possenti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Krishnan_V/0/1/0/all/0/1">V. Venkatraman Krishnan</a> The SUrvey for Pulsars and Extragalactic Radio Bursts ran from 2014 April to 2019 August, covering a large fraction of the southern hemisphere at mid- to high-galactic latitudes, and consisting of 9-minute pointings taken with the 20-cm multibeam receiver on the Parkes Radio Telescope. Data upRead More →

Heavy-metal Jupiters by major mergers: metallicity vs. mass for giant planets. (arXiv:2006.12500v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Ginzburg_S/0/1/0/all/0/1">Sivan Ginzburg</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chiang_E/0/1/0/all/0/1">Eugene Chiang</a> Some Jupiter-mass exoplanets contain $sim$$100, M_oplus$ of metals, well above the $sim$$10, M_oplus$ typically needed in a solid core to trigger giant planet formation by runaway gas accretion. We demonstrate that such `heavy-metal Jupiters’ can result from planetary mergers near $sim$10 au. Multiple cores accreting gas at runaway rates gravitationally perturb one another onto crossing orbits such that the average merger rate equals the gas accretion rate. Concurrent mergers and gas accretion implies the core mass scales with the total planet mass as $M_{rm core} proptoRead More →

Discovery of Extended Tidal Tails around the Globular Cluster Palomar 13. (arXiv:2006.12501v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Shipp_N/0/1/0/all/0/1">Nora Shipp</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Price_Whelan_A/0/1/0/all/0/1">Adrian Price-Whelan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tavangar_K/0/1/0/all/0/1">Kiyan Tavangar</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mateu_C/0/1/0/all/0/1">Cecilia Mateu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Drlica_Wagner_A/0/1/0/all/0/1">Alex Drlica-Wagner</a> We use photometry from the DECam Legacy Survey to detect candidate tidal tails extending ~5 deg on either side of the Palomar 13 globular cluster. The tails are aligned with the proper motion of Palomar 13 and are consistent with its old, metal-poor stellar population. We identify three RR Lyrae stars that are plausibly associated with the tails, in addition to four previously known in the cluster. From these RR Lyrae stars, we find that the meanRead More →

Risks for Life on Proxima b from Sterilizing Asteroid Impacts. (arXiv:2006.12503v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Siraj_A/0/1/0/all/0/1">Amir Siraj</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Loeb_A/0/1/0/all/0/1">Abraham Loeb</a> We consider the implications that a debris belt located between Proxima b and Proxima c would pose for the rate of large asteroid impacts that could sterilize Proxima b from life. Future observations by ALMA or JWST could constrain the existence of an asteroid belt in the life-threatening regime. We generalize our rate calculation of sterilizing impacts for habitable planets in systems with an asteroid belt and an outer planet. We consider the implications that a debris belt located between Proxima b and Proxima c would poseRead More →